There is a long history of manufacturers producing treats and chews for dogs. One of the main attributes of chew type products is a toughness and flexibility to the point where it takes the dog a long time to consume the product. Numerous pig and cattle body parts such as bones, ears, hooves and skin have been used to produce palatable dog treats with extended chew times. A great majority of the chew style products have been based on rawhide. While rawhide presents an economical starting material, it is not particularly palatable to dogs, particularly smaller species which tend to be more finicky in nature. Manufacturers have attempted to solve this problem of reduced acceptability by incorporating numerous ingredients and processing techniques into the manufacture of rawhide based chews for dogs.
The basic problem however remains. As ingredients or processing techniques are utilized with rawhide to increase palatability, they typically weaken the basic structure of the rawhide and produce a less acceptable product from the standpoint of extended chew time. What is needed is a method or composition which can utilize rawhide in its relatively un-weakened state but still present a highly palatable product to the pet.
The prior art demonstrates a long history of utilizing rawhide in dog chews, Fisher (U.S. Pat. No. 2,988,045) demonstrated the basic techniques of how rawhide can be separated at the tannery and split into layers that can be formed into shapes followed by dehydration to produce a shelf-stable rawhide chew for dogs. A wide range of rawhide chew style products followed, teaching various forms, shapes and methods for utilizing a basic rawhide fraction as a dog chew. This included Lehn (U.S. Pat. No. 4,702,929) which teaches a method for extruding rawhide byproduct fraction, called spetches, with starch to form a dog chew in stick form. Spanier (U.S. Pat. No. 5,047,231) teaches a method of soaking an inorganic pyrophosphate salt into rawhide to form a chew capable of reducing tartar accumulation on the dog's teeth. Perlberg (U.S. Pat. No. 6,223,693) demonstrates a method of soaking rawhide in a humectant and soft edible binder to produce a flexible edible chew. Twain (U.S. Pat. No. 6,425,348) taught a method for producing a chewable pet shelter from rawhide which incorporated chemical flavoring which would appeal to the pet.
Kirch (U.S. Pat. No. 6,840,196) demonstrates a pet chew produced by folding a first sheet of rawhide around a second sheet of rawhide. The second sheet is impregnated with a flavoring and protrudes from under the first sheet of rawhide. This system served to increase the palatability of the chew while at the same time reduced the incident of rug staining which can be a problem when the flavoring is present on the surface of the product.
Hingst (U.S. Pat. No. 6,895,900) disclosed a combination rawhide and pigskin product where sheets of rawhide and pigskin are sandwiched or intertwined together to form a treat with improved flavor. Jia (U.S. Pat. No. 6,935,275) teaches a method for producing a dog treat by rolling a precut and flavored rawhide piece into a cylinder with strips of hide extending from the outer ends of the cylinder. And, Hague (U.S. Pat. No. 6,886,497) disclosed a product and method for infusing a rawhide or pigskin with a mint, or chlorophyll, flavoring and applying perforations to the hide so that a dog's teeth would penetrate into the product to assist in the cleaning of the dog's teeth.
Some of the most commercially successful products utilizing rawhide as dog treats have taken the approach of incorporating a meat fraction in conjunction with the rawhide to significantly increase the palatability of the chew. Sherrill (U.S. Pat. No. 5,673,653) disclosed a product and process of wrapping jerky sheets on the inside of a roll of rawhide. The jerky fraction protruded from the ends and the horizontal seam of the outside layer so that the dog could quickly be subjected to the flavor of the dehydrated meat fraction. This product has been successfully commercialized under the trade name “Dingo”. Only a small portion of meat fraction however is initially available to the dog and the manufacturing method of rolling sheets of rawhide inside sheets of jerky significantly reduce the quantity of meat that can be incorporated on a dry weight basis.
Greenburg (U.S. Pat. No. 5,635,237) teaches a method of melting rawhide scraps inside of a twin-screw extruder and producing ropes that can be cut and tied to produce a formulated knotted rawhide bone. While small quantities of meat or flavoring can be incorporated with this method, the necessity to feed the extruder at a reduced moisture level limits the amount of meat fraction that can be included. Andersen (U.S. Pat. No. 6,277,420) demonstrates a method of making a preformed rawhide tube and depositing a shelf-stable liquid meaty filling into the cavity of the tube which gels and then forms a solid matrix on the inside of the rawhide. While this system incorporates large ratios of meaty filling fraction to rawhide, the chew time is somewhat reduced by the high moisture present in the system. Brown (U.S. Pat. No. 6,886,496) has attempted to solve this problem by producing a pre-extruded dried meaty log that could be placed inside of a rolled rawhide cylinder. While this would result in a somewhat extended chew time over many of the earlier treats, a limited fraction of meat is available on the surface of the final chew to maintain a dog's interest for an extended period of time.